Accelerated sea ice loss in the Arctic due to global heating is allowing carbon dioxide absorption at rates three to four times higher than in any other open sea or ocean anywhere on the planet. The resulting rapid decline in pH is already contributing to the rapid collapse of Arctic Ocean ecosystems.
With record high temperatures happening throughout the globe and especially so in the Arctic, ice in the region is already melting at some of the fastest rates ever. It opens the Arctic waters for more CO2 absorption and rendering the marine ecosystem environment more acidic than ever. Photo: Pixabay
The increased acidification and its primary causes are outlined in detail in a new study published on September 29, 2022, by researchers from China’s Polar and Marine Research Institute at Jimei University and the School of Marine Science and Policy at the University of Delaware.
Because of unique meteorological conditions at the northern pole and continually rising levels of greenhouse gas emissions, it was recently discovered the Arctic is warming at a rate four times faster than the planetary average for the last 43 years, in a process known as Arctic amplification. In two separate studies published in July 2022, it was revealed that two previously unreported surges in Arctic temperatures had occurred in 1986 and 1999. Those temperature jumps have contributed to a far more rapid decline in Arctic sea ice coverage during the summer months, substantially cutting overall sea ice coverage in through the winter.
Less sea ice causes a decrease in the regional albedo, the relative reflectivity of sunlight from the surface of the ocean. That raises surface temperatures in the Arctic Ocean, contributing to a cycle of more energy absorption which then melts even more ice.
Exposed areas of the oceans collectively absorb roughly one-third of all excess carbon dioxide being dumped into the atmosphere by fossil fuel emissions. With less sea ice in the Arctic than in the past, this is now allowing even CO2 into the Arctic oceans.
That then drives accelerating acidification of the Arctic waters. Added to the higher surface temperatures of the oceans and the decreased availability of oxygen to many of the life forms, this is projected to cause catastrophic harm to marine life above the Arctic circle.
These are the conclusions of the new research project just reported on by author Wei-Jun Cai, a University of Delaware expert in marine chemistry.
The researchers conducted their analysis by studying Arctic and other ocean data available for the period from 1994 to 2020. What they discovered was not necessarily a surprise, since the Arctic warming and carbon dioxide emissions trends were already well understood. But what did cause alarm was the speed at which the changes in the Arctic Ocean were happening.
“In other ocean systems, acidification is being driven by an increase in atmospheric carbon dioxide, which is increasing at a rate of around 2ppm [parts per million] per year,” said Cai during a recent interview about the work.
“In lower latitudes,” the scientist explained further, “you have coral reefs and if you add carbon dioxide to the water, the carbon saturation rate will increase and the coral won’t grow.”
In the Arctic, he went on, the process is different because the melting sea ice itself becomes part of the equation.
“The ice melt dilutes or lowers the alkalinity of the seawater. This dilutes the buffering capacity of the water, its ability to resist acidification,” Cai said. As a result, though the trend of the results was already suspected, he continued, “We were shocked to see acidification is happening three to four times faster [compared to in other oceans].”
The scientists also pointed out that the increased acidification may have its own side effects contributing to biological decline in the Arctic. One is that metals suspended in the water will change their nature without the alkaline buffering which is more normal. That could make them more toxic, poisoning the Arctic ocean biome further.
Cai pointed out that as acidification tied to carbon dioxide absorption increases, the habitat and ecosystems which used to thrive in the past may see a rapid deterioration in ability to support life in the coming decades.
“We are far from knowing what the cost is for biological systems,” Cai said. “We don’t know what organisms could be affected. This is something the biological community needs to look into.”
The paper describing this research, “Climate change drives rapid decadal acidification in the Arctic Ocean from 1994 to 2020,” by Di Qi, Zhangxian Ouyan, and Wei-Jun Cai, et. al., was published in the journal Science on September 29, 2022.